The Increase in the Elastic Range and Strengthening Control of Quasi Brittle Cement Composites by Low-Module Dispersed Reinforcement: An Assessment of Reinforcement Effects.

This paper presents the possibility of using low-module polypropylene dispersed reinforcement (E = 4.9 GPa) to influence the load-deflection correlation of cement composites. Problems have been indicated regarding the improvement of elastic range by using that type of fibre as compared with a composite without reinforcement. It was demonstrated that it was possible to increase the ability to carry stress in the Hooke's law proportionality range in mortar and paste types of composites reinforced with low-module fibres, i.e., Vf = 3% (in contrast to concrete composites). The possibility of having good strengthening and deflection control in order to limit the catastrophic destruction process was confirmed. In this paper, we identify the problem of deformation assessment in composites with significant deformation capacity. Determining the effects of reinforcement based on a comparison with a composite without fibres is suggested as a reasonable approach as it enables the comparison of results obtained by various universities with different research conditions.

Analysis of Tensile Strength of Double Helix Wires / 대한정형외과학회잡지

PURPOSE: To compare the tensile properties of double helical twisting. MATERIALS AND METHODS: 21G and 18G stainless steel wires were used. Monostrand, untwisted double strand and manually twisted double helix wires were tested under gradually increasing tension force until the wires break. Data were analyzed by using a computer system to get force-strain curves. RESULTS: Forces at the break point showed no significant differences between untwisted double strand wires and helically twisted double strand wires. Forces at the yield point deformation were proportionally increased to the degree of helical twisting until the wires were twisted 20 times (piptch number: 24/10 cm) with no more increase after then. Final strain at break point decreased by helical twisting, which means the range of plastic deformation decreased. CONCLUSION: By helical twisting, the wires increase in elastic range and decrease in plastic deformation. Therefore, double helix wiring seemed to be a more effective method of fixation compared to the untwisted double strand wires.